1.  Construct two lines that intersect and are not perpendicular.  Label the lines r and s.  Label the angles as in the figure below.

2.    Angles BAC and DAE are vertical angles.  
        Angles EAB and CAD are vertical angles. 
        Describe these angles, and write a definition for vertical angles.

3.    Measure all of the angles.  Compare angles BAC and DAE.  Compare angle EAB and CAD.  What do you notice?
        What can you conclude about the measures of vertical angles?

4.  Angles BAC and CAD are adjacent angles.  
        Angles CAD and DAE are adjacent angles. 
        Angles DAE and EAB are adjacent angles.
        Angles EAB and BAC are adjacent angles.
        Describe these angles, and write a definition for adjacent angles.

5.    Compare the measures of each pair of adjacent angles.  What do you notice?
        For each pair, add the two angle measures together.  What can you conclude?
        Each pair of adjacent angles are supplementary angles.  
        Write a defintion for supplementary angles.